As the complexity and density of integrated circuits have increased, the number of input/output (I/O) terminals has also increased. For example a 32 bit microprocessor may require 130 to 190 I/O terminals, while a 128 bit microprocessor may require 500 to 1000 I/O terminals. The cost of packages for high I/O count devices increases faster than the number of I/O pins. That is, the increased cost is much more than proportional to the increase in pin count. Therefore it is highly desirable to package only known good integrated circuit dice in the expensive high-pin-count packages.
Accordingly, it has become a highly desirable practice by semiconductor device manufacturers to burn-in and test integrated circuit devices before mounting them in their packages and shipping to customers, thereby identifying known good devices. The tests and burn-in are often done at elevated temperatures and/or humidity. Higher stress conditions are used in a desire to ensure that any early failures occur during the burn-in and test and not after shipment of the devices to customers.
It is often desirable to use TAB or flip chip technology for high I/O integrated circuit devices, to allow smaller packages and better interconnection reliability. For IC's made using TAB or flip chip technology, standard conventional test sockets are not usable for the burn-in and testing, as such IC's do not have I/O pins until they are packaged. Also, IC chip dice with TAB bond pads as close as 0.001 or 0.002 inch center-to-center are very difficult to make contact with conventional probe cards. Therefore, it is difficult to adopt the practice of packaging only known good dice that have passed burn-in testing for IC devices using TAB or flip chip technology. Thus a need exists for methods that allow burn-in and testing of IC devices using TAB technology or flip chip technology, to identify known good dice before they are mounted in expensive packages with high I/O count. Methods for burn-in and testing that can eliminate wafer probing from the process are especially needed.